title: 3'-Deoxy-3'-18F-fluorothymidine PET for the early prediction of response to leucovorin, 5-fluorouracil, and oxaliplatin therapy in patients with metastatic colorectal cancer.
abstract: The aim of this study was to evaluate 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) PET for early prediction of the standard anatomic response and survival outcomes in patients with metastatic colorectal cancer (mCRC) receiving leucovorin, 5-fluorouracil (5-FU), and oxaliplatin (FOLFOX).
  
  
  METHODS
  The main eligibility criteria included histologically confirmed mCRC, ≥ 1 extrahepatic measurable lesions, and no prior chemotherapy in a metastatic setting. Chemotherapy consisted of leucovorin on day 1, followed by the continuous infusion of 5-FU on days 1 and 2, and oxaliplatin on day 3. In the second and subsequent cycles of chemotherapy, oxaliplatin was administered simultaneously with leucovorin on day 1. (18)F-FLT PET scans were obtained 3 times during the first cycle of chemotherapy: before chemotherapy, 24 h after infusion of 5-FU (day 2), and 48 h after completion of chemotherapy (day 5). The maximum standardized uptake value (SUVMAX) of (18)F-FLT was measured. Treatment responses were assessed by CT after 3 cycles of FOLFOX.
  
  
  RESULTS
  Eighteen patients were included in the study. The response rate after 3 cycles of FOLFOX was 27.8% (5/18). The SUVMAX was increased in responders (P = 0.043) and nonresponders (P < 0.001) on day 2 and was decreased, compared with baseline values, on day 5 in responders only (P = 0.043). Receiver-operating-characteristic curve analysis indicated that the use of a threshold of an SUVMAX increase on day 2 of ≤ 45.8% resulted in a sensitivity of 100%, specificity of 69.2%, and relative risk of 2.250 (P = 0.029) for the diagnosis of responders. Use of a threshold of an SUVMAX decrease on day 5 of ≥ 10.6% resulted in a sensitivity of 100%, specificity of 76.9%, and relative risk of 2.667 (P = 0.007). Patients with low (18)F-FLT flare tended to have longer survivals than patients with high flare (2-y overall survival rate, 77.8% vs. 44.4%; P = 0.051).
  
  
  CONCLUSIONS
  The (18)F-FLT flare observed during 5-FU infusion was associated with poor treatment response in patients with mCRC. The degree of (18)F-FLT flare might be used to predict the outcome of patients who receive infusional 5-FU-based chemotherapy.
authors.affiliation: Department of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
authors.forename: Yong Sang
authors.initials: YS
authors.lastname: Hong
authors.forename: Hye Ok
authors.initials: HO
authors.lastname: Kim
authors.forename: Kyu-pyo
authors.initials: KP
authors.lastname: Kim
authors.forename: Jae-Lyun
authors.initials: JL
authors.lastname: Lee
authors.forename: Hwa Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Seung Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Sang Ju
authors.initials: SJ
authors.lastname: Lee
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Oh
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Kim
authors.forename: Jin-Sook
authors.initials: JS
authors.lastname: Ryu
authors.forename: Dae Hyuk
authors.initials: DH
authors.lastname: Moon
authors.forename: Tae Won
authors.initials: TW
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D015224:Dideoxynucleosides; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use; D006801:Humans; D002955:Leucovorin / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009944:Organoplatinum Compounds / Q000627:therapeutic use; D049268:Positron-Emission Tomography; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015224:Dideoxynucleosides; D009944:Organoplatinum Compounds; C002854:alovudine; D002955:Leucovorin; D005472:Fluorouracil
keywords: 18F-fluorothymidine; 5-fluorouracil; metastatic colorectal cancer; oxaliplatin; positron emission tomography